Method for coating porous polyurethane resin

Abstract

A method for coating a porous polyurethane resin substrate with an aromatic isocyanate coating composition is provided comprising the steps of (i) providing a porous substrate of a polyurethane foam resin comprising at least one surface upon which the aromatic isocyanate coating composition is to be applied; (ii) applying at least one coating of a primary layer to the substrate surface, the primary layer comprising an aqueous solution of a compound that includes at least one —OH reactive group in its non-aqueous, dry state, and capable, upon drying, of forming a self-supporting, continuous film on the substrate surface at room temperature; (iii) optionally subjecting the applied primary layer to forced drying conditions at a temperature below the softening point of the porous polyurethane resin substrate; and (iv) after allowing the primary layer to substantially dry, applying a secondary layer comprising an aromatic isocyanate compound to the primary layer to form a continuous, film-forming coating on the substrate surface, preferably one having the property of being water-impermeable or water-impermeable and water vapor-permeable.

1 . A method for coating a porous polyurethane resin with an aromatic isocyanate coating composition comprising the steps of: 
 (a) providing a porous polyurethane resin substrate comprising at least one surface upon which the coating composition is to be applied;    (b) applying one or more primary layers to said substrate surface, said primary layer comprising an aqueous solution of a compound that includes at least one —OH reactive group in its non-aqueous, dry state, which is capable, upon drying, of forming a self-supporting, continuous film on said substrate surface at room temperature;    (c) optionally subjecting the applied primary layer to forced drying conditions at a temperature below the softening point of said porous polyurethane resin; and    (d) after allowing the primary layer to substantially dry, applying a secondary layer to the primary layer, said secondary layer comprising an aromatic isocyanate compound containing one or more reactive —NCO groups for reaction with the —OH reactive group in the primary layer;    wherein a continuous, film-forming coating is formed on said substrate surface.    
     
     
         2 . The method according to  claim 1  wherein multiple coatings of the primary layer are applied to said substrate surface.  
     
     
         3 . The method according to  claim 1  wherein the primary layer comprises an aqueous solution of polyvinyl alcohol or polyvinyl alcohol/polyvinyl acetate copolymer, the polyvinyl acetate component of the copolymer being present in an amount of 1-14 weight percent.  
     
     
         4 . The method according to  claim 3  wherein the concentration of the polyvinyl alcohol or polyvinyl alcohol/polyvinyl acetate copolymer solution is about 0.5 to 5.0 percent by weight.  
     
     
         5 . The method according to  claim 1  wherein the primary layer comprises an aqueous solution of carboxymethylcellulose.  
     
     
         6 . The method according to  claim 5  wherein the concentration of the carboxymethylcellulose solution is about 1 to 3 percent by weight.  
     
     
         7 . The method according to  claim 5  wherein the concentration of the carboxymethylcellulose solution is about 1.8 to 2.2 percent by weight.  
     
     
         8 . The method according to  claim 1  wherein the primary layer comprises an aqueous solution of starch.  
     
     
         9 . The method according to  claim 8  wherein the concentration of the starch solution is about 1 to 8 percent by weight.  
     
     
         10 . The method according to  claim 9  wherein the concentration of the starch solution is about 3 to 5 percent by weight.  
     
     
         11 . The method according to  claim 1  wherein the primary layer comprises an aqueous solution of sodium or ammonium polyacrylate.  
     
     
         12 . The method according to  claim 11  wherein the concentration of the sodium or ammonium polyacrylate solution is about 10 to 51 percent by weight and the sodium or ammonium polyacrylate has a molecular weight range of about 2,000 to 6,000.  
     
     
         13 . The method according to  claim 12  wherein the concentration of the sodium or ammonium polyacrylate solution is about 20 to 41 percent by weight.  
     
     
         14 . The method according to  claim 1  wherein the primary layer comprises an aqueous solution of polyacrylic acid.  
     
     
         15 . The method according to  claim 14  wherein the concentration of the polyacrylic acid solution is about 10 to 41 percent by weight and the polyacrylic acid has a molecular weight range of about 2,000 to 6,000.  
     
     
         16 . The method according to  claim 15  wherein the concentration of the polyacrylic acid solution is about 20 to 41 percent by weight.  
     
     
         17 . The method according to  claim 1  wherein the primary layer comprises an aqueous solution of sodium polycarboxylate.  
     
     
         18 . The method according to  claim 17  wherein the concentration of the sodium polycarboxylate solution is about 10 to 41 percent by weight and the sodium polycarboxylate has a molecular weight range of about 2,000 to 170,000.  
     
     
         19 . The method according to  claim 18  wherein the concentration of the sodium polycarboxylate solution is about 20 to 41 percent by weight.  
     
     
         20 . The method according to  claim 1  wherein the primary layer comprises an aqueous solution of an alkyl acrylate or alkyl methacrylate compound.  
     
     
         21 . The method according to  claim 20  wherein the concentration of the alkyl acrylate or alkyl methacrylate solution is about 5 to 40 percent by weight and the alkyl acrylate or alkyl methacrylate has a molecular weight range of about 5,000 to 10,000.  
     
     
         22 . The method according to  claim 21  wherein the concentration of the alkyl acrylate or alkyl methacrylate solution is about 10 to 20 percent by weight.  
     
     
         23 . The method according to  claim 1  wherein the primary layer comprises an aqueous solution of gum arabic.  
     
     
         24 . The method according to  claim 23  wherein the concentration of the gum arabic solution is about 5 to 40 percent by weight.  
     
     
         25 . The method according to  claim 1  wherein the aromatic isocyanate coating composition is in the form of a water-based, polyurethane paint.  
     
     
         26 . The method according to  claim 1  wherein the aromatic isocyanate coating composition is in the form of a solvent-based, polyurethane paint.  
     
     
         27 . The method according to  claim 1  wherein the porous polyurethane resin has a density in the range of about 0.002 to 1.000 kilograms per cubic meter.  
     
     
         28 . A method for preparing a reactive film-forming surface on a porous polyurethane substrate for bonding with a coating composition comprising an aromatic isocyanate compound, comprising the steps of 
 (a) providing a porous polyurethane substrate comprising a density of from about 0.002 to about 1.000 kilograms/cubic meter and at least one surface for preparing the reactive film-forming surface thereon;    (b) applying to the surface of the porous polyurethane substrate, at least one layer comprising an aqueous solution of a compound that includes at least one —OH reactive group in its non-aqueous, dry state, said layer being capable, upon drying, of forming a self-supporting, continuous film on said substrate surface at room temperature; and    (c) optionally subjecting the layer to forced drying conditions at a temperature below the softening temperature of the substrate.    
     
     
         29 . The method according to  claim 28  wherein more than one layer of the aqueous solution is applied to said substrate surface.  
     
     
         30 . The method according to  claim 28  wherein the layer comprises an aqueous solution of polyvinyl alcohol or polyvinyl alcohol/polyvinyl acetate copolymer, the polyvinyl acetate component of the copolymer being present in an amount of 1-14 weight percent.  
     
     
         31 . The method according to  claim 30  wherein the aqueous concentration of the polyvinyl alcohol or polyvinyl alcohol/polyvinyl acetate copolymer is about 0.5 to 5.0 percent by weight.  
     
     
         32 . The method according to  claim 28  wherein the layer comprises an aqueous solution of carboxymethylcellulose.  
     
     
         33 . The method according to  claim 32  wherein the aqueous concentration of the carboxymethylcellulose solution is about 1 to 3 percent by weight.  
     
     
         34 . The method according to  claim 32  wherein the aqueous concentration of the carboxymethylcellulose solution is about 1.8 to 2.2 percent by weight.  
     
     
         35 . The method according to  claim 28  wherein the layer comprises an aqueous solution of starch.  
     
     
         36 . The method according to  claim 35  wherein the aqueous concentration of the starch solution is about 1 to 8 percent by weight.  
     
     
         37 . The method according to  claim 35  wherein the aqueous concentration of the starch solution is about 3 to 5 percent by weight.  
     
     
         38 . The method according to  claim 28  wherein the layer comprises an aqueous solution of sodium or ammonium polyacrylate.  
     
     
         39 . The method according to  claim 38  wherein the concentration of the sodium or ammonium polyacrylate solution is about 105 to 51 percent by weight and the molecular weight range of the sodium or ammonium polyacrylate is about 2,000 to 10,000.  
     
     
         40 . The method according to  claim 39  wherein the concentration of the sodium or ammonium polyacrylate solution is about 20 to 41 percent by weight.  
     
     
         41 . The method according to  claim 28  wherein the layer comprises an aqueous solution of polyacrylic acid.  
     
     
         42 . The method according to  claim 41  wherein the concentration of the polyacrylic acid solution is about 5 to 41 percent by weight and the molecular weight range of the polyacrylic acid is about 2,000 to 170,000.  
     
     
         43 . The method according to  claim 42  wherein the concentration of the polyacrylic acid is about 20 to 41 percent by weight.  
     
     
         44 . The method according to  claim 28  wherein the layer comprises an aqueous solution of sodium polycarboxylate.  
     
     
         45 . The method according to  claim 44  wherein the concentration of the sodium polycarboxylate solution is about 10 to 41 percent by weight and the molecular weight range of the sodium polycarboxylate is about 2,000 to 170,000.  
     
     
         46 . The method according to  claim 45  wherein the concentration of the sodium polycarboxylate solution is about 20 to 41 percent by weight.  
     
     
         47 . The method according to  claim 28  wherein the layer comprises an aqueous solution of an alkyl acrylate or alkyl methacrylate compound.  
     
     
         48 . The method according to  claim 47  wherein the concentration of the alkyl acrylate or alkyl methacyrlate solution is about 5 to 40 percent by weight and the molecular weight range of the alkyl acrylate or alkyl methacrylate compound is about 5,000 to 10,000.  
     
     
         49 . The method according to  claim 48  wherein the concentration of the alkyl acrylate or alkyl methacyrlate solution is about 10 to 20 percent by weight.  
     
     
         50 . The method according to  claim 28  wherein the layer comprises an aqueous solution of gum arabic.  
     
     
         51 . The method according to  claim 50  wherein the concentration of the gum arabic solution is about 5 to 40 percent by weight.  
     
     
         52 - 101 . (canceled)  
     
     
         102 . The method according to  claim 1  wherein the aromatic isocyanate compound is 4,4′-diphenyl-methane diisocyanate.  
     
     
         103 . The method according to  claim 1  wherein the aromatic isocyanate compound is hexamethylene diisocyanate.  
     
     
         104 . The method according to  claim 1  wherein the aromatic isocyanate compound is selected from the group consisting of 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, 0-tolidine diisocyanate, xylylene disocyanate (XDI), hydro xylylene diisocyanate, and hydro 4,4′-diphenylmethane diisocyanate.  
     
     
         105 . The method according to  claim 1  wherein the secondary layer additionally comprises an anti-hydrolysis agent.  
     
     
         106 . The method according to  claim 105  wherein the anti-hydrolysis agent is a polycarbodiimide.  
     
     
         107 . The method according to  claim 1  wherein the secondary layer additionally comprises a weather-resistance agent.  
     
     
         108 . The method according to  claim 107  wherein the weather-resistance agent is {tetrakis [methylene-3-(3′5′-ditert-butyl-4′-hydroxylphenyl) propionate]methane}.  
     
     
         109 . The method according to claims  1  or  28  wherein the drying conditions occur at a temperature in the range of from 50° C. to 60° C.  
     
     
         110 . The method according to claims  1  or  28  wherein the respective primary layer and reactive film-forming layer comprises a compound selected from the group consisting of polyvinyl alcohol or polyvinyl alcohol/polyvinyl acetate copolymer, carboxymethylcellulose, starch, sodium or ammonium polyacrylate, polyacrylic acid, sodium polycarboxylate, a alkyl acrylate or alkyl methacrylate compound, and gum arabic.  
     
     
         111 . The method according to  claim 1  wherein the secondary layer is in the form of a water-based, polyurethane paint.  
     
     
         112 . The method according to  claim 1  wherein the secondary layer is in the form of a solvent-based, polyurethane paint.